This invention relates to internal combustion engines and, more particularly, to valve systems for supplying a fuel/air mixture from a carburetor or fuel injection system to the engine cylinders and for removing exhaust gasses from the cylinders to an exhaust manifold or exhaust pipes.
The most common type of valve train employs two or more reciprocal mushroom valves positioned over each of the engine cylinders and the valves are operated by a cam, push rods and rocker arms to open and close in a timed sequence. Typical mushroom valve engines employ two valves per cylinder, one valve for the intake mixture and the other valve for exhaust gasses. More recent engine designs employ four valves per cylinder, two intake valves and two exhaust valves, for increasing the volumetric efficiency of the engine. While providing four valves per cylinder head increases the volumetric efficiency of the engine and resultant engine power, such increased efficiency is achieved at the cost of engine complexity and expense, increased overall engine weight, and minimized effect in reducing pollutants output by the engine.
Attempts have been made to produce a more economical and efficient valve train for combustion engines and such attempts typically employ a rotary valve as exemplified in U.S. Pat. Nos. 5,205,251, 5,152,259, 4,949,685, and 4,036,184. While many of such rotary valve designs would be more economical and produce fewer pollutants than mushroom valve engines, such rotary valves have relatively limited port sizes and have been less than successful in providing sufficient volumetric efficiency to maintain acceptable levels of engine power. It is believed that most of such rotary valves are not even capable of providing the amount of engine power commonly associated with mushroom valve engines that employ two valves per cylinder.
An important aspect of this invention therefore lies in the discovery of a relatively uncomplicated and highly efficient rotary valve capable of providing high volumetric efficiency and high engine power of the level commonly associated with four valve per cylinder engines. Such results are accomplished by providing a cylindrical rotary valve having an intake passageway extending from a first end of the valve to an intake port and an exhaust passageway extending from an exhaust port to a second end of the valve. The intake passageway is provided with intake acceleration means for supercharging the fuel/air mixture into the cylinder and the exhaust passageway is provided with exhaust acceleration means for efficiently removing exhaust gasses from the cylinder. Such a construction is relatively uncomplex in design, is compact and lightweight and results in a valve train that produces high volumetric efficiency and high engine power.
In brief, the rotary valve of the present invention comprises a generally elongated cylindrical unitary body having a longitudinally extending axis of rotation and defining an intake port and an exhaust port. In multi-cylinder engines, a plurality of such unitary bodies are mounted transversely in an engine head above each of the cylinders so that the intake and exhaust ports of each of the unitary bodies periodically or cyclically communicate with the respective cylinders as the unitary body is rotated. The unitary body defines an intake passageway extending from a first end of the unitary body, which receives the fuel/air mixture from an intake manifold, to the intake port which communicates with the cylinder as the valve is rotated. The unitary body also defines an exhaust passageway extending from an exhaust port which communicates with the cylinder and a second end of the unitary body which communicates with an exhaust manifold or pipe. Intake acceleration means are disposed in the intake passageway for accelerating the flow of the fuel/air mixture through the intake passageway and supercharging that mixture through the intake port and into the cylinder head. Similarly, exhaust acceleration means are disposed in the exhaust passageway for accelerating the flow of exhaust gasses out of the cylinder and through the exhaust passageway to the exhaust manifold or pipe.
In a preferred embodiment, the intake acceleration means take the form of a first generally helically-shaped blade disposed in the intake passageway along the axis of rotation so that rotation of the valve and the helical blade draws the fuel/air mixture through the intake passageway and supercharges that mixture into the cylinder head. Similarly, the exhaust acceleration means take the form of a second generally helically-shaped blade disposed in the exhaust passageway along the axis of rotation to draw exhaust gasses from the cylinder head and facilitate their removal through the exhaust passageway and into the exhaust manifold or pipe. To further facilitate the intake of the fuel/air mixture, the intake acceleration means may also include a plurality of forwardly curved fan blades extending radially outward from the axis of rotation at the first end of the unitary body, each of the fan blades being positioned adjacent to one of a plurality of openings that communicate with the intake passageway. Optimally, the fan blades are mounted in an intake housing to draw the intake mixture from the intake manifold into the intake passageway.
In the preferred construction, the unitary body includes two main components: (1) a cylindrical tube having an outer wall that defines the intake and exhaust ports; and (2) dividing means for defining the intake and exhaust passageways within the cylindrical tube. The dividing means preferably take the form of a generally rectangular central divider plate aligned along the axis of rotation and having a pair of oppositely extending transverse flanges at each of its ends which divide the first half of the cylindrical tube into the intake passageway and the second half into the exhaust passageway. In such a construction, the helically-shaped blades of the intake and exhaust acceleration means extend oppositely outward from the opposite ends of the divider plate along the axis of rotation and into the respective intake and exhaust passageways.
In another embodiment, the rotary valve of this invention may be provided with automatic port overlap adjustment means for gradually or incrementally reducing the diameter of a portion of the outer wall between the intake and exhaust ports to allow gasses from the cylinder to simultaneously communicate with both the intake and exhaust ports as the rotational speed of the unitary body increases. Providing such a port overlap means results in a rotary valve in which little or no port overlap exists at idle or lower speeds but an increasing port overlap is provided at higher speeds to increase the volumetric efficiency of the rotary valve when it is required. Such a construction is greatly advantageous over prior art valve systems in which the amount of port overlap presented a compromise between a minimal overlap which is desirable at idle or lower speeds and a larger degree of overlap which is desirable at higher speeds. Such a compromise resulted in a valve system that did not provide optimal performance at the low and high ends of the operating speed spectrum. In contrast, the automatic port overlap means of this invention overcomes that deficiency by providing a variable overlap that self-adjusts for optimal operating conditions at both low and high speeds.
In a preferred form, the automatic port overlap means take the form of a T-shaped member having a stem portion which extends into an elongate edge of the divider plate and having an arcuate integral cross-member which forms the portion of the cylindrical wall between the intake and exhaust ports. The cross-member has a pair of opposite edges which each respectively define at least one edge of the intake and exhaust ports. Retraction means are provided for gradually retracting the stem of the T-shaped member into the divider plate as the rotational speed of the unitary body increases. This incrementally retracts the cross-member between the intake and exhaust ports which provides an increasing overlap at increasing speeds, providing greater volumetric efficiency for the engine as required.
In another embodiment, the intake port of the unitary body may be advantageously provided with expansion means for increasing the size of the intake port at high rotational speeds. In a preferred construction, the intake port expansion means take the form of a spring-loaded generally T-shaped flap having a stem extending into the cylindrical wall of the unitary body and having a head portion which defines an edge of the intake port. As the rotational speed of the unitary body increases, centrifugal force causes the spring-loaded T-shaped flap to retract into the cylindrical wall along with the head portion which increases the size of the intake port.
In another advantageous embodiment, turbine means are provided for further increasing the efficiency of the rotary valve of this invention. In such a construction, the first end of the rotary valve communicates with an intake housing and the second end of the rotary valve communicates with an exhaust housing. The turbine means include a turbine shaft in the head that extends parallel to the rotational axis of the rotary valve, a first turbine blade mounted on one end of the shaft in the intake housing, and a second turbine blade mounted at the other end of the shaft in the exhaust housing. In operation, the exhaust gasses flowing through the second end of the rotary valve rotate the second turbine blade which in turn rotates the first turbine blade. This creates a positive pressure in the pathway of the fuel/air mixture which supercharges that mixture into the intake passageway, thereby increasing the volumetric efficiency of the valve and the resultant engine power.
Other advantages, features, and objects of the invention will become apparent from the specification and drawings.